A single bubble trapped in an acoustic standing wave can be made to undergo
highly nonlinear volume mode pulsations resulting in inertial cavitation---the
expansive growth and violent collapse of bubbles. Under certain conditions the
collapse results in light emission called sonoluminescence (SL). Though much has
been studied regarding properties of the emitted light, little work has been
done on the acoustic emission from such a bubble. Previous measurements [Cordry
et al., J. Acoust. Soc. Am. 98, 2921(A) (1995)] using a needle hydrophone show
only a general low-level acoustic signature. In the present study, a broadband,
nonfocused transducer is used to record the acoustic emission from single
bubbles at various acoustic drive amplitudes in the SL and non-SL producing
regions. The typical acoustic signature includes a large amplitude pulse
corresponding to the initial collapse followed by smaller amplitude pulses
corresponding to the rebounds. The rebounding bubble essentially oscillates at
its resonance frequency so that the simple measurement of the time interval
between rebounds makes it relatively easy to measure one of the fundamental
unknowns of a sonoluminescence bubble---its equilibrium radius. [Work supported
by NSF and ONR.]